Rheostat for arc-lamps.



J. J. WOOD.

RHEOSTAT FOR ARG LAMPS.

APPLICATION FILED APR. 25. 1903.

22 i ,al WITNESSES:

PATBNTBD JUNE 30, 1903.

,3g A 35 lli INVENTOR:

UNITED STATES latented .fune 30, 1903.

JAMES J. WOOD, OF FORT WAYNE, INDIANA.

RHEOSTAT FOR ARC-LAMPS.

SPECIFICATION forming part Of Letters Patent NO. 732,489, dated June 30,1903.

Application filed April 25,1903. Serial No.f154,197. (No model.)

To a/ZZ whom, it may concern:

Beitknown thatI, JAMESJ-WOOD, acitizen of the United States, residing atFort Wayne, in the county of Allen and State of Indiana, have inventedcertain new and useful Improvements in Rheostats'for Arc-Lamps, (to. ofwhich the followingis a specification.

This invention relates to rheostats or resistances especially designedand adapted for use with electric-arc lamps, but applicable in part toother uses.

Arc-lamps for use on constant-potential circuits are provided with auexternal resistance, which usually and preferably is contained in aspecial box or case, which coinmonly is arranged above the lamp orlampcase, the connecting-wires being extended between the respectivecases. The externalresistance case or box has to be adapted forsupporting a considerable length of resistance-wire in such manner as tofacilitate the disengagement and radiation of a considerable quantity ofheat, this being especially important in a series lamp, where thecoinpensating resistance consumes practically the same amount of energywhen the lamp is extinguished that is consumed in the lamp when it is inoperation, this energy being converted into heat, which is radiated fromthe resistance-wire.

My invention provides certain improvements, pertaining chieiiy to theconstruction of the resistance-case and the support and insulation ofthe resistant wire, designed to afford free ventilation and ready escapeof the heat.

The accompanying drawings show my invention as adapted to an arc-lamp.

Figure l is an elevation of the lamp as a whole. Fig. 2 is a verticalsection of the upper portion of the lamp-case and of theexternal-resistance case. Fig. 3 is a horizontal section through theexternal-resistance case, the resistant Wire being omitted. Fig. Liis avertical section of the resistance-case or rheostatin a plane atrightangles to that of Fig. 2.

Referring to Fig. l, A designates the lampcase, andB theexternal-resistance oase. The lamp-case A is constructed at the top Witha hood A', beneath which is attached a plate a', to which plate isfastened the central tube C of the lamp. H is the inner or arc-inclosingglobe, and Q is the outer globe, held by a globe-holder Q.

The rheostat or resistance-case B is mounted on top of the lamp-case, sothat it serves as the medium for suspending the latter. The hood A ofthe lamp-case is formed atits upper part With a tubular neck, and theresisrance-case has at its bottom a tubular base fitting it. Therheostat has as its support a cast shell D, which is covered over at thetop bya cap or hood 30 and inclosed within a cylindrical sheet-metalcasing or shell 40. The casting D is formed at its bottom with a neck21, which fits on the neck 22 of the hood A', so that, as shown in Fig.2, there is formed a communicating passage between the interior of thehood and the lower part of the resistance-case, from which two passages24 24, Fig. 2, lead through the casting D to the exterior thereof. Thereis thus provided a clear passage for the respective wires communicatingbetween the resistance-coil in the box B and the electrical elementsinclosed Within the lamp-case A, whereby these wires are oarriedinternallyinstead of being extended externally between the lamp-case andthe resistance-box. The casting D is formed at its bottom with aperforated flange 25, above which is a cylindrical shell 26, extendingup to any suitable height, its dimension being variable according to thelength of the resistantcoil which is to be provided for. Around-theexterior of the shell 26 are arranged vertical insulating andheat-resisting `tubes 27 27 to any desired number, these tubes beingpreferably arranged as close together as can be, with or without actualcontact. To guide these .tubes and retain them parallel, it ispreferable to form the casting D with vertical ribs 28, which projectpartly between the tubes and determine their correct spacing and keepthem properly inplace.' The tubes are held against the casting by anysuitable means, preferably by bands 29, of wire, Wound around theentireseries of tubes and binding them against the cylindrical shell. Tokeep the tubes from'slipping down in case the heat relaxes the bands, aflange or foot 28a s--carried circumferentially around the shell 26 andcomes just beneath the lower ends of the tubes. The tubes are coveredand inclosed by the outer sheet-metal Wall or shell 40,

which is fastened at any suitable number of points by screws 41 engagingthe iiange 25. The resistant wire is coiled into a helix of such sizethat it will enter freely within the tubes 27.. This coil or helix 3l isthen extended through the tubes, passing upwardly through one, thendownwardly through the next, upwardly through the next, and so on aroundthe entire series, its opposite ends being joined to wires which extenddown and join the lamp-circuit. The heat which is generated by thecurrent passing through the resistance-coil 31 is in part conducted awayby currents of air circulating upwardly through the tubes 27 and in partis communicated to these tubes, which are preferably of porcelain, andtherefore good heat-conductors, the tubes conducting the heat to theshell or casting D, which in turn radiates it to the air. To facilitatethe dissemination of this heat, the shell or casting D is formed withvertical ribs 35 at intervals, these being arranged preferably toproject inwardly, as shown in Fig. 3, into the space or chamber withinthe cylindrical part 26, and this space or chamber is open at bottom andtop, so as to constitute an air-flue through which the air may ascend,being caused to circulate by the heat imparted to it, and in ascendingflowing over the surfaces of the ribs 35, so as to conduct away the heattherefrom. By reason of the shell 26 being of cast metal it has suchmass as to rapidly absorb heat from the tubes 27 and conduct it to theflanges 35. The cap-plate 30 is arranged to cover over the annularseries of tubes, so as tc prevent any rain falling on the resistantwire, while its central portion is left open to afford free escape forthe air ascending through the central chamber within theresistance-case. Thus the cap 30 .forms an annular portion 36, whichcovers the series of tubes, but is so far separated therefrom on boththe outer and inner sides as to permit of free escape of the air, which,entering the perforations through the ange 25, ascends through theltubes 27 and between these tubes and the outer shell 40 and escapesfrom beneath the dependent flanges ot' the annular portion 36 of thecap. For suspending the lamp the cap is provided with ears 37, betweenwhich is confined the usual insulator 38 for the suspension-ring 39. Theears 37 are joined by a base connected by four arms or spokes 4l to theannular portion 36, and the cap is fastened to the casting D by screws,as shown in Fig. 2, which enter post 42. The casting D is in turnfastened to the hood A by means of a central screw 43, which screws intoa boss on a cross-bar 44, crossing the neck 22 of the hood. A

The described construction of resistancecase is well adapted to rapidlyradiate the heat which is generated in the resistancecoils, since ampleopportunity is afforded for the free upward circulation 0f air and amplesurface is provided for the radiation of heat to the air.

It must not be inferred from the particularity of detail with which Ihave herein described the preferred embodiment of my invention that I amby any means limited to the mechanical 'details herein set forth, sincemy invention is susceptible of a wide range of modification withoutdeparting from its essential features.

1. A rheostat comprising a body-shell having an upright wall, a seriesof upright insulating-tubes supported thereagainst, and aresistance-coil extended through said tubes.

2. A rheostat com prisiug a body-shell having an upright wall, a seriesof upright insulating-tubes supported thereby, open at top and bottom,and a helically-wound resistant wire extended back and forth through thesuccessive tubes.

3. `A rheostat comprising a body-shell having an upright wall, a seriesof upright porcelain tubes supported against said wall, and aresistance-wire in vsaid tubes.

4. A rheostat comprising an upright bodyshell, a series of uprightinsulating-tubes supported thereagainst, open at top and bottom forcirculation of air through them, and a resistance-coil extendedcontinuously through said tubes, passing up through one, down throughthe next, and so on.

5. A rheostat comprising an upright wall of cast metal havingheat-radiating anges project ing therefrom,insulating-supports fastenedagainst said wall, and a resistance carried by said supports.

6. A rheostat comprising an upright wall of cast metal havingheat-radiating anges projecting therefrom, insulating-tubes fastenedagainst said Wall, and a resistance-wire in said tubes.

7. A rheostat comprising an upright bodyshell, a series of uprightinsulating-tubes supported thereagainst, an outer wall adjacent to andinclosing said tubes, with an air-space between, and a resistance coilextended through said tubes, with openings at bottom and top forcirculation of air around said tubes between said shell and outer wall.

8. A rheostat comprising a body-shell having an upright cylindricalportion, a perforated ange projecting beyond the same at its bottom, aseries of insulating-tubes supported against said shell above saidflange, and an outerwall attached to said flange and inclosing saidtubes.

9. A rheostat comprising a body-shell having an upright cylindricalportion with a circumferential flange near its bottom, and a se- IOO IIO

ries of insulating-tubes supported against said shell above said flange,whereby said flange engages their lower ends and prevents theirdisplacement.

10. A rheostat comprising a body-shell having an upright cylindricalportion, a series of insulating-tubes su pported against said shell, anda cap-plate for said shell covering the tops of said tubes and adaptedto prevent entrance of rain thereinto.

1l. A rheostatcompri sing a body-shell having an upright cylindricalportion, a series of insulating-tubes supported against said shell, anouter Wall inclosing said tubes, adapted to adinitvupward circulation ofair through and around said tubes, and a cap-plate covering the upperends of said tubes, spaced apart therefrom to permit escape of theascending air, and adapted to exclude rain.

12. A rheostat comprising a bod y-shell having a cylindrical portion, aseries of insulating-tubes arranged against the outer side of saidcylindrical portion, and a band around the exterior of said series oftubes, whereby they are fastened against said shell.

13. A rheostat comprising a cylindrical portion having parallel exterioriianges, and a series of insulating-tubes arranged against saidcylindrical portion, and entering the spaces between said anges, andfastened against said shell.

14. A rheostat comprisinga body-shell and a series of insulating-tubesarranged against said shell, said shell formed with projections atintervals engaging said tubes to hold them in place.

15. A rheostat comprisinga body-shell, having an uprighttubularVportion, open at bottom and top to form an air-flue within it, andhaving upright heat-radiating flanges projectingfromitsinnersurfaceintosaid air-flue.

1G. A rheostat comprising a b0dy-shell,hav ing an upright tubularportion, open at bottom and top to form an air-Hue within it, hav.- ingat its bottom a central base, and having vertical ribs projectinginwardly from said tubular portion and joining said base,where by toconnect the shell and caseand to conduct heat from the shell into saidflue, and radiate it to the ascending air.

17. A rheostat comprising a body-shell having an upright tubular portion26, a central hollow base 21, and integral passages 24,' 24,communicating from the interior of said base to the exterior of saidtubular portion.

In Witness whereof I have hereunto signed 5o my name in the'presence oftwo subscribing witnesses.

JAMES J. WOOD.

Witnesses:

W. H. CRIGH'roN, A. L. HADLEY.

